Chapter 9: What is Strength X A Nen User's Battle
In Roy's experience, demons were no more frightening than humans. In fact, humans were often far more vicious.
But the demons of this world were different. They weren't just twisted people; they were physical monsters, Magical Beasts whose existence was tied to a single progenitor—the Demon King, Muzan Kibutsuji. Empowered by his blood, their physical bodies were vastly superior to any normal human's.
But like a Nen ability bound by Vows and Restrictions, this great power came with great limitations.
First, their lives were tied to the will of their king. He could destroy them with a single thought.
Second, they were fatally vulnerable to sunlight. This weakness forced them to be nocturnal predators, which was the very reason Old Man Saburo had insisted Tanjiro stay the night, inadvertently saving him from the massacre that claimed his family.
Third, they were hemophagic, subsisting entirely on human blood. Starvation would weaken them, but a fresh meal could restore them to their peak in an instant.
Unfortunately for Roy, the demon before them was one that had just finished a full-course meal. It was at its absolute peak.
And it's still daytime, Roy thought, marveling at his own 'good' luck. A thick layer of clouds had completely obscured the sun, giving the creature the confidence to hunt in the snow-covered forest.
"Bro... what is that thing?" Tanjiro's voice was a terrified whisper, his hand gripping the hem of Roy's haori.
"You said it yourself," Roy replied, his voice calm. "A demon."
"A real demon?! Then we have to—run!"
"Run?" Roy didn't turn. "Run where? You plan on leading it back to the house?" He shifted his grip, hoisting the hand-axe onto his shoulder and taking a deliberate step forward.
"I..." Tanjiro, who had already started to turn, froze in place.
His brother's voice cut through the cold air, leaving no room for argument. "Stay here."
In the next instant, Roy was gone. Using Shadow Step, he crossed the 300-meter distance in a series of explosive leaps, becoming a blur of motion, a gale of wind and snow that shot directly towards the creature.
The demon sensed him coming. It tossed aside the half-eaten corpse of the woodcutter, its blood-red eyes fixing on the approaching boy. A grin split its face, revealing a row of sharp fangs.
"Heh heh heh... perfect timing!" it rasped. "This old man's meat was stringy. But you two... you'll be nice and tender."
The demon let out a guttural laugh. Instead of retreating, it stomped a foot into the ground, kicking up a crater of snow, and launched itself forward like a cannonball. It met Roy's charge head-on, its claws, sharper than any knife, slashing down at his head.
The speed was terrifying. Tanjiro screamed. "Bro, look out!"
A whoosh of air passed a hair's breadth from Roy's neck. At the last possible second, he had activated Rhythm Echo. His body flickered, leaving behind a solid after-image as the real Roy reappeared at the demon's flank. He brought the hand-axe around in a powerful, horizontal arc.
THWACK! The blow landed with the sound of a cleaver hitting a side of beef.
The demon howled in pain and surprise, rolling away to put distance between them. It didn't understand. How could a mere human move in a way that defied the laws of physics? It scrambled back to its feet, the gaping wound on its side already knitting itself shut, steaming in the cold air.
Tanjiro, peeking from behind a tree, saw the wound regenerate in seconds. His heart sank. How could you possibly fight something that couldn't be injured?
But Roy didn't seem to notice. He spun the hand-axe in a casual flourish, a predatory smile touching his lips. He was becoming more and more excited.
[Notice: Combat Experience +1]
[Current Level: Combat LV2 (16/100)]
[Note: Bonus experience may be allocated to mastered Assassin Arts (Shadow Step, Rhythm Echo, Snake Awakens).]
This isn't a demon, Roy thought, his eyes gleaming. It's a walking experience farm.
He gained a new layer of understanding of his own Nen ability. "Absorbing nourishment" wasn't just about learning. Combat was a part of it, too.
So the only question is, do I kill it quickly, or do I play with my food for a bit?
Roy already knew the answer. He pointed the head of his axe at the demon ten meters away. The creature, seeing the taunt, felt an inexplicable shiver run down its spine. It didn't understand why it was suddenly feeling... fear. The emotion infuriated it.
In his human life as Sato Takeichiro, he'd never feared anyone! He'd even killed a samurai from a daimyo's court! To be turned into a demon, only to be intimidated by a child with an axe... if that man ever found out, he would be mercilessly disposed of for his weakness.
"Heh heh heh... you're looking down on me, brat," Sato hissed, flexing his ankles. The initial exchange had told him everything he needed to know. The boy was fast and had some kind of weird movement technique. To win, he just had to be faster. More unpredictable.
And "fast" and "unpredictable" were his specialties.
"Blood Demon Art—Ricochet Carnage!" Sato's body changed. The soles of his feet warped, bending into a concave, spring-like shape. With a light touch on the snow, he launched himself into the air as if propelled by a powerful spring.
What happened next would be seared into Tanjiro's memory for the rest of his life.
The forest was suddenly filled with dozens of after-images of the demon. They ricocheted from tree to tree, each bounce accompanied by the stench of blood and a gust of wind, their movements a chaotic, three-dimensional storm of violence. It was so fast that Tanjiro rubbed his eyes, but he couldn't tell which one was real. All he could do was clench his fists in helpless terror.
"Oh no, Bro... it can make clones just like you!"
No... it's not the same.
Roy's eyes were coated in a layer of aura. He had activated Gyo. He could see what Tanjiro couldn't.
The demon was using the reactive force from its spring-like feet, bouncing off the trees and the ground to generate phantoms through sheer, overwhelming speed. His own Rhythm Echo was an illusion that exploited the blind spots in an opponent's vision. In terms of raw velocity, the demon was far superior.
But what Sato Takeichiro could never have imagined was that he wasn't facing some talented martial artist.
He was facing a true Nen user, one whose Aura Nodes had been fully awakened.
And what was a Nen user?
A Nen user could use Gyo to see the flow of aura, to distinguish the real from the fake. A Nen user could use Ten to maintain a state of perfect mental calm. And a Nen user could use their aura to empower their attacks, strengthening their body and their weapon to an absurd degree.
So, my foolish, dear little brother, allow me to teach you your first real lesson.
Roy took a deep, steadying breath and raised the hand-axe.
His voice was perfectly calm. "Watch closely, Tanjiro."
"Because true strength... is the one thing that will never lie to your eyes."
And with that, he swung.